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Monitoring Well and Sparge Point Installation Report—Former Unocal Service Station#0187 July 15,2002 the well Copies of the monitoring well observation summary and sampling field data sheets are included in Appendix D Wellhead Survey Following installation of the wells, the top of casing and vault box elevations of all newly installed wells were surveyed by Morrow Surveying (license #5161) The horizontal locations, including GPS longitude and latitude, of all newly installed wells were measured A copy of the surveyor's report is included in Appendix E RESULTS OF THE SUBSURFACE INVESTIGATION Soil encountered during this investigation consisted of interbedded silt, clay, and sand to the total depth explored A distinct color change occurs in soil at approximately 55 feet bgs, where soil is brown above that depth and dark gray below that depth Soil encountered during this investigation is similar to previous investigations at and in the vicinity of the site Groundwater in well U-26 stabilized at the depth of 28 95 feet below top of casing Detailed descriptions of the soil encountered during drilling are presented on the boring logs in Appendix C CHEMICAL ANALYTICAL RESULTS A total of eight soil samples from the monitoring well boring, one composite soil sample from the stockpiled drill cuttings, and one groundwater sample were submitted under chain-of-custody for chemical analysis Analyses were performed by Sequoia Analytical (ELAP #1271 and #1624) Copies of the laboratory reports and chain-of-custody forms are included in Appendix F Soil and groundwater chemical analytical results are summarized in Tables l and 2, respectively Chemical Analytical Procedures All soil and groundwater samples were analyzed for TPHg, benzene, toluene, ethylbenzene, and xylenes (BTEX), and MtBE by DHS LUFT Methods Groundwater samples were also analyzed for ethanol, tert-butyl alcohol (TBA), MtBE, di-isopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) by EPA Method 8260B As required by the disposal facility, the stockpiled drill cutting's composite sample was analyzed for TPHg, BTEX, and MtBE by DHS LUFT Methods, and total lead by EPA Method 6010B Soil Analytical Results TPHg, BTEX, or MtBE were not detected in soil samples from the well boring U-26 Groundwater Analytical Results TPHg, benzene, ethanol, TBA, DIPE, ETBE, or TAME were not detected in groundwater from well U-26 MtBE was reported in well U-26 at a concentration of 2 0 ppb by EPA Method 8260B 24004211-1 5